This invention relates to the sequencing of DNA strands.
In one class of techniques for sequencing DNA, identical cloned strands of DNA are marked. The strands are separated into four batches and either individually cleaved at or synthesized to one of the four base types, which are adenine, guanine, cytosine and thymine (hereinafter A, G, C and T).
The adenine-, guanine-, cytosine- and thymine-cleaved batches are then electrophoresed for separation. The rate of electrophoresis indicates the DNA sequence.
In a prior art sequencing technique of this class, the DNA strands are marked with a radioactive mark, cleaved at a different base type in each aliquot, and after being separated by electrophoresis, film is exposed to the gel and developed to indicate the sequence of the bands. The range of lengths and resolution of this type of static detection is limited by the size of the apparatus.
In another prior art sequencing technique of this class, single strands are synthesized to a different base type in each aliquot, and the strands are marked radioactively for later detection.
It is also known in the prior art to use fluorescent markers for marking proteins and to pulse the fluorescent markers with light to receive an indication of the presence of a particular protein from the fluorescence.
The prior art techniques for DNA sequencing have several disadvantages such as: (1) theyare relatively slow; (2) they are at least partly manual; and (3) they are limited to relatively short strands of DNA.